Ellen Pompeo doesn't really get why she's so famous. "I don't find acting to be a particularly noble way to make a living," says the actress, who just started her third season on Grey's Anatomy. "I'm not saving anybody's life, I'm not a teacher, I'm not working for UNICEF. I don't think I'm some big deal."

Tell that to the 20 million-plus fans who watch the ABC hit. Surely she can forgive them for being a tad obsessed with the gal behind the titular Dr. Meredith Grey, who ended last season torn between sweet steady Chris O'Donnell and her married on-off lover Patrick Dempsey, a.k.a. Dr. McDreamy. "I am on a great TV show," she admits. "It took me a long time to get here."

The actress, 36, who grew up in the blue-collar town of Everett, Mass., got a late start in the field. "Where I come from, you don't just say, 'Oh, I'm going to become an actor,'" says the understated Pompeo, who became a bartender after high school. "Talk like that and they think you're crazy." But at 24, she took the plunge, with encouragement from her father, Joseph, a salesman for Lorillard Tobacco. "He always told me you can do anything you want to do," says Pompeo, whose mom died at 37 when she was just 4 years old.

At first, Pompeo made a living doing TV ads for companies like Citibank and L'Oréal and in small roles on TV (Law & Order) and film (Old School) before finally hitting the jackpot with Grey's. "I've lived enough of my life without money that I really appreciate it," says the actress, who recently bought herself a Tuscan-style home in Los Angeles. The perks aren't bad either, like going to this year's Emmys, where Grey's was up for 11 awards (and scored one win). "The whole night was a highlight," she says. "Seeing my friends so happy and so dressed up. It was such a nice moment."

But then there's the flip side of being successful in Hollywood. Accused by the tabloids of everything from being underweight to being a diva on the Grey's set, Pompeo feels "like I'm being attacked," she says. "They say I'm too thin or not a nice person. It's like, 'Jeez—what did I do to you?'"

As for rumor No. 1, Pompeo says she's been teased about her weight her entire life. "Growing up, I was horribly self-conscious about how skinny I was," she says. "You think it's never going to be as horrible as sixth, seventh, eighth grade when all the other girls are getting boobs. Now all of a sudden it's back to people saying things to me again. I can't shake it."

Pompeo, who is 5′7″ and estimates her weight to be 100 lbs. ("I don't own a scale," she says), does yoga three times a week and weight trains to add muscle. "I have to gain size because everyone thinks I'm anorexic," she whispers in mock horror. But she eats plenty, she insists over eggs and hotcakes at an L.A. coffee shop. As if to punctuate her point, she also orders a chicken salad sandwich to go. "All these reports make me so paranoid, I'm going to become an overeater," she says. Equally distraught about the rumors is Pompeo's sister Maureen, who says the whole family is thin: "It's infuriating when I see comments about her weight. Ellen loves to eat—her first word [as a baby] was 'pepperoni.'"

Equally ridiculous, says Pompeo, are those rumors that she doesn't get along with her castmates. "One of the reasons the show works is you can see the chemistry between everybody," she says. Her costars, in fact, readily sing Pompeo's praises. "She's one of the most beautifully spirited people that I know," says Chandra Wilson (Dr. Miranda Bailey). So no diva tendencies here? No way, adds Justin Chambers (Dr. Alex Karev). "She's from Boston—she's a broad."

A broad who would much rather spend an evening with her fellow Bostonite boyfriend Chris Ivery, 37, a record producer, than go to the latest hot spot. "We had a great day yesterday," says Pompeo. "We walked on the beach, then we came home, took a shower and went out for sushi. Then we laid on the couch with the dogs and watched TV."

She and Ivery met through pals in L.A. in 2003, but didn't date right away. "We were friends for six months; then one night she just looked different to me," says Ivery, who grew up minutes away from Pompeo but never crossed paths with her. "We were six degrees our whole lives, so I feel like we were sort of meant to be," she says. Then she adds—with those pesky tabloids in mind—"We'll get married eventually, secretly."